The Tekhelet and Its Renewal

The Tekhelet and Its Renewal https://bluefringes.s3.amazonaws.com/wp-content/uploads/2026/02/19044235/sariel.jpg 470 265 Rafi Hecht Rafi Hecht https://secure.gravatar.com/avatar/95feb92509e3b334e0a67a7b730419ef4697414cbfa423f9a82c022e65ae871a?s=96&d=mm&r=g February 19, 2026 July 28, 2026

From https://www.yeshiva.org.il/midrash/34264

Translated from the original Hebrew: https://bluefringes.com/2026/02/19/%d7%94%d7%aa%d7%9b%d7%9c%d7%aa-%d7%95%d7%97%d7%99%d7%93%d7%95%d7%a9%d7%94/

HaRav Shmuel Ariel
Iyar 5777
70 Minute Read

Summary: Tekhelet and Its Renewal

What the article is trying to answer

Chazal describe tekhelet as a required element of tzitzis, produced from the chilazon. The article asks what we can say today about restoring tekhelet: Do we have enough certainty about the chilazon, the dye, and the halachic requirements to bring it back into practice?

Core sources

The Torah commands tzitzis and adds “petil tekhelet” (a tekhelet thread). • The Gemara (primarily Menachos) discusses how tekhelet is made, from what creature, and how it is used in the strings. • Rishonim (Rambam, Raavad, Tosafos, etc.) and later poskim address the definition of tekhelet, the chilazon, and practical halachah.

1) Is tekhelet an obligation today?

The article frames tekhelet as a full חיוב when genuine tekhelet is available. The practical question is not whether tekhelet is part of the mitzvah, but whether we can identify it with sufficient clarity. It addresses the claim of “no mesorah” and argues that for certain mitzvos (especially ones dependent on identifying an object), Halachah often relies on סימנים, מסורת segments that were lost, and strong evidence rather than an unbroken practice.

2) What is the chilazon?

The Gemara gives identifying סימנים: it lives in the sea, comes up periodically, its “blood” (dye fluid) is used for tekhelet, and tekhelet is expensive. The article reviews candidates raised historically and focuses on the murex trunculus (a sea snail) as the best fit for the Chazal description when you combine the סימנים with archaeological and chemical findings.

3) What color is tekhelet?

The article discusses the well-known debate about tekhelet’s exact shade: pure blue, blue-with-a-violet cast, etc. It argues that the sources point to a color in the blue family, and that multiple blue shades can still fall under “tekhelet” in the halachic/linguistic sense, much like other Torah color terms that cover a range.

4) Chemistry and practical dyeing

A major modern development is the ability to reliably produce a blue dye from murex, including by using light/UV exposure and specific processing steps. The article treats this as a strong point: the same creature long associated with ancient purple dyes can, under the right conditions, produce a stable blue tekhelet-like dye.

5) Historical evidence

The article surveys archaeological and historical data: Mediterranean dye industry remains, findings of dyed textiles, and the broad ancient association between similar snails and prestigious blue/purple dyes. It uses this evidence as supporting context for the identification, not as the sole basis for halachah.

6) Halachic risk: what if it’s wrong?

One concern is wearing something that is not tekhelet and calling it tekhelet. The article weighs this risk against the risk of permanently leaving out a Torah-required element. It argues that if the identification is strong, the default should move toward doing the mitzvah as described, while being honest about the nature of the evidence.

Bottom line

The Hebrew article’s overall conclusion is that the murex-based tekhelet has substantial halachic and evidentiary support, and that restoring tekhelet is a serious and defensible halachic position.

Body

Tekhelet and its Renewal – Mareh-it English (All Sections, Footnotes Inlined)

Format: Original line breaks preserved; each former footnote reference is inlined in parentheses for continuous reading.

Section 1 (א): What is tekhelet, and from where did Chazal learn that tekhelet is specifically from the chilazon?

The mitzvot that depend on tekhelet

Before we get into the discussion of tekhelet, let’s note the mitzvot where it is needed:

Tekhelet appears in tzitzit:

“Speak to Bnei Yisrael and tell them that they should make for themselves tzitzit on the corners of their garments, for their generations, and they should place on the corner tzitzit a thread of tekhelet.”

(Bamidbar 15:38)

And similarly in the Mishkan and in the Mikdash—both for the parokhot and the Mishkan itself, and for the bigdei kehuna:

“And from the tekhelet, the argaman, and the tola’at shani they made the serad garments to serve in the Kodesh, and they made the holy garments for Aharon…”

(Shemot 39:1)

As we see, in the Mishkan, together with tekhelet there is also argaman and tola’at shani. But those are needed only for the Mikdash (and for the tahara of a metzora), so after the Churban they were barely dealt with. Tekhelet, though, is needed also for tzitzit, which applies in our time, so it appears much more in halakhic literature, and there were many more attempts to identify it. (We won’t deal here with identifying argaman and tola’at shani; a broad discussion appears in “Tzefiyah”, vol. 5, published by Machon HaMikdash.)

From what is tekhelet produced?

The Tosefta (Menachot perek 9; halakha 16 in the Zuckermandel edition; Vilna perek 9 halakha 6) says:

“Tekhelet is kosher only from the chilazon; if one brought it from something that is not the chilazon, it is non-kosher.”

And this also comes out clearly from the Gemara in a number of places—

In Menachot 44a it says about the chilazon:

“…and with its blood they dye tekhelet; therefore its price is expensive.”

Meaning: the only kosher source for producing tekhelet is the chilazon, and that is why its price is high.

And more than that—the Gemara says in a few places (Bava Metzia 61b; Menachot 40a, 41b, 43a) that there is a dye that looks like tekhelet, “kela ilan”, and this dye is non-kosher for tzitzit, even though it looks exactly like tekhelet and you can’t tell them apart by eye. In other words: not every thread that is the color of tekhelet is kosher for tzitzit; tekhelet has to be produced specifically from a certain source—from the chilazon.

From where did Chazal learn that tekhelet is produced specifically from a chilazon?

We have to ask: from where did Chazal learn that tekhelet needs to be produced specifically from a chilazon? In our simple understanding, “tekhelet” is the name of a shade—and if so…

On this, we find two main approaches among the Rishonim. (A third approach is that of Sefer Yere’im, siman 401, p. 221 in the Vilna edition, who explains that the source is… )

The Rambam (Hilchot Tzitzit, perek 2 halakha 1–2) writes (all quotations from the Rambam here follow the “Yad Peshutah” edition, with added punctuation):

“Tekhelet mentioned in the Torah anywhere is wool dyed like the ‘patukh’ shade found in kohl.” (Kohl is something placed on the eye for healing or for adornment.)

“And the tekhelet mentioned regarding tzitzit needs to be dyed with a known dyeing that stays in its beauty and does not change. Anything not dyed with that dyeing is non-kosher for tzitzit, even if it looks like tekhelet.”

“How do they dye tekhelet for tzitzit? They take wool… and afterward they bring the blood of the chilazon…”

Meaning: the word “tekhelet” on its own means wool dyed a sky-like color, regardless of what the source of that color is; but for tzitzit there is a special din that it needs a specific, known dyeing…

Rashi, in his commentary to the Torah (Shemot 25:4), writes:

“Tekhelet: wool dyed with the blood of the chilazon, and its color is yarok.” (In the language of Chazal and the Rishonim, “yarok” includes what we call today green, yellow, and blue.)

Meaning: this is the פירוש of the word “tekhelet”—specifically wool dyed with the blood of a chilazon. In our language, “tekhelet” is a certain shade; there is a garment in tekhelet color, there is a tekhelet-colored flower, etc.—but that is not how the Torah is using the term here…

This seems strange to us, because we are used to using the word “tekhelet” as a shade. But if you look carefully at the pesukim, it looks clearly like this is the name of a material.

“And this is the terumah that you shall take from them: gold, and silver, and copper; and tekhelet, and argaman, and tola’at shani, and fine linen…”

Everything listed here is a material, and it doesn’t make sense to list colors in such a list. Do you say: “take from them blue”? You have to explain tekhelet here as a material—wool dyed in a certain way.

“And from the tekhelet, the argaman, and the tola’at shani they made the serad garments to serve in the Kodesh…”

(Shemot 39:1)

Does it make sense to say: “and from the blue… they made garments”? Of course garments are made from some substance, not from a color. And this is proven from other pesukim as well; nowhere does the Torah speak of “tekhelet” the way one speaks of a color word.

Even the Rambam, at root, holds like this—that the word “tekhelet” is not just a shade-name, but a material. After all, his wording is: “tekhelet mentioned in the Torah anywhere is wool dyed…”

We can lay out a few nafka minot in halakha between Rashi’s approach and the Rambam’s approach:

Regarding tzitzit—some understand the Rambam to mean (Tiferet Yisrael on the Mishnah, introduction to Seder Mo’ed, “Rules of the Holy Garments of the Kehuna”, s.v. “Amnam…”) that…
And on the other side—if one dyed wool from a chilazon but the dyeing didn’t come out well, and the color is not lasting: according to Rashi there is no פסול, because the requirement is…
A clear nafka mina is with the bigdei kehuna. The plain reading of the Rambam is (and most Acharonim understood him this way; see discussion in the article of Avi Mor…) that:

“…tekhelet mentioned anywhere is wool dyed like the color of the sky, which is ‘patukh’ from kohl.”

He does not mention the condition that it must be a lasting dyeing and must come from a chilazon; he mentions only the shade.

And this comes out clearly from his wording in Hilchot Tzitzit, in the halakha quoted above:

“Tekhelet mentioned in the Torah anywhere is wool dyed like the ‘patukh’ shade in kohl…”

“And the tekhelet mentioned regarding tzitzit needs to be dyed with a known dyeing that stays in its beauty and does not change…”

“How do they dye tekhelet for tzitzit? … they bring the blood of the chilazon…”

The Rambam explicitly distinguishes in his wording between tekhelet mentioned anywhere in the Torah—where you only need the correct shade (“patukh shebe-kohl”)—and the tekhelet of tzitzit, which has extra requirements.

But according to Rashi’s approach, certainly even the bigdei kehuna need tekhelet specifically from a chilazon—if the meaning of “tekhelet” is “wool dyed with the blood of a chilazon” in the first place.

When you look carefully at the sources, it seems to me that there are (in my humble opinion) a few proofs for Rashi’s approach. We’ll bring one of them.

According to the Rambam, tekhelet is dyed from a chilazon because there is a special halakhah that it must be a lasting dye (tzevi’ah amedah). Still, you can ask: from where did Chazal learn that tekhelet needs specifically a lasting dye? But according to Rashi, you don’t need to look for a separate source at all for where Chazal learned that tekhelet is produced specifically from the chilazon—because that is the meaning of the word “tekhelet.” And if so, it’s obvious that you need specifically chilazon. Just like “zahav” is zahav and “dam” is dam, so too “tekhelet” is from the chilazon, and no special derivation is needed for that.

And so too among the Acharonim, it seems that the accepted approach is like Rashi—that “tekhelet” is specifically from chilazon. כך, in discussions about renewing the avodah of the korbanot, they mention that one of the problems that needs to be solved is finding the chilazon of tekhelet. And likewise regarding tzitzit, the poskim did not dye “tekhelet” using the synthetic dyes that were developed in our times, even though they are very lasting. Rather, they assumed פשוט that you need specifically chilazon, and not any other dye.

Section 2 (ב): The history of tekhelet and the main identifications that were suggested

When did tekhelet disappear, and why?

At some point, tekhelet stopped being available in Eretz Yisrael. The exact date is not clear, but it seems it was still around during the period of Chazal, as the Gemara discusses it as something practical and known (for example, Menachot 43a–44a).

Later sources already speak about tekhelet as something we no longer have, and for many generations the accepted practice in Klal Yisrael was to wear only white strings.

Several explanations are suggested in the literature:

Roman and later Byzantine decrees that restricted (or even forbade) the production and use of the precious purple/blue dyes, which were tied to imperial clothing.
Political and economic changes around the Mediterranean that disrupted the coastal dye industry.
The long-term reality that the dye production required specialized knowledge and infrastructure, and once the chain was broken, it was hard to rebuild.

The tekhelet of Radzyn — the cuttlefish (“diyunon”)

In recent generations, the first major attempt to renew tekhelet was by the Admor of Radzyn, R’ Gershon Ḥanokh Leiner zt”l.

He wrote extensively on the subject, especially in his sefer “Sefunei Temunei Ḥol,” and he even travelled to the coastal areas of southern Italy to investigate possible candidates.

His identification was that the “chilazon” is the cuttlefish (Sepia), known in the language of the Roke’ach as “diyunon.”

The cuttlefish has an ink sac, and by extracting the black fluid and processing it through a chemical procedure, he produced a blue dye that he used for tzitzit.

He argued that this method was consistent with the descriptions of Chazal and with the ancient dye industry.

Many of his followers accepted this tekhelet, and in some circles it continues until today.

At the same time, Rav Yitzḥak HaLevi Herzog zt”l already argued in his doctoral work that the Radzyn dye is not an organic dye extracted from the animal, but rather a synthetic dye created through chemical reaction.

If so, even if the animal itself is a “chilazon” of some sort, the dye is not the “dam chilazon” that Chazal describe.

Rav Herzog and the Janthina snail

Rav Herzog’s classic work on tekhelet (his dissertation, later expanded and published in Hebrew) is the foundation for almost all modern discussion.

He surveyed the sources in Chazal, the Rishonim, and also the historical and scientific evidence.

Rav Herzog strongly leaned toward the general “argaman” family of sea snails (what we call today murex/hexaplex type snails) as the likely source of tekhelet, because these were the famous ancient dye snails of the Mediterranean.

However, in his time he did not succeed in producing a stable blue dye from them, and because of that (together with several difficulties he raised from Chazal’s descriptions), he suggested another candidate: the Janthina snail.

Janthina is a sea snail that floats on the surface of the ocean using a bubble “raft,” and it produces a bluish-purple secretion.

Rav Herzog suggested that this might explain certain descriptions (such as the idea of the chilazon “rising” or being found near the surface).

Nevertheless, he did not practically restart tekhelet production based on this suggestion, and it remained more a theoretical proposal.

The Argamon Kehe Kotzim / Murex trunculus (“Ptil Tekhelet”)

In our time, the most widespread renewed tekhelet is produced from the sea snail commonly called Murex trunculus (today often classified as Hexaplex trunculus).

In Hebrew it is known as “argamon kehe kotzim.”

This identification is not a modern invention.

Already in the nineteenth century, researchers associated the famous Tyrian purple dyes with murex-type snails, and in the twentieth century this became standard in the scientific literature.

In the Torah world, the renewed attention came through people who studied both the sugyot and the research, and who then worked to produce tekhelet in practice.

The key point is that the snail has a gland that produces a clear fluid.

When the fluid is exposed to air and sunlight, it undergoes chemical change.

If processed in the right way, the result is a blue dye (and not only purple).

This discovery answers the main scientific difficulty that Rav Herzog faced in his day.

Based on this, “Ptil Tekhelet” and other producers began manufacturing tekhelet strings from this snail, and many talmidei ḥakhamim and yirei Shamayim adopted it.

In the next sections we will lay out the proofs and deal with the main objections that are raised.

Section 3 (ג): Proofs that the chilazon of tekhelet is the Argamon Kehe Kotzim (Murex / Hexaplex trunculus)

We can build the identification from several independent “tracks” of evidence.

Each track stands on its own, and when they all point to the same creature, that convergence becomes a very strong proof.

Track A — From Chazal: what does “chilazon” mean?

From a number of places in Chazal, it is clear that “chilazon” is the category-name for a shelled snail.

a) Shir HaShirim Rabbah says:

“Learn from the chilazon: just as it grows, its sheath grows with it” (Shir HaShirim Rabbah 4:11).

A creature whose “sheath” grows together with it is exactly a snail whose shell expands as it grows.

b) In Sanhedrin 91a, the Gemara tells a story about a “chilazon” that is found in the mountains, and it “comes out” specifically after rainfall.

This is obviously not a sea creature.

It is describing a land snail.

Once we see that Chazal use “chilazon” for a land snail, the conclusion follows: the “chilazon” of tekhelet is the sea-version of that same type of creature — a sea snail.

This point already rules out several modern proposals, because a cuttlefish is not a “chilazon” in the sense Chazal are using here, and a floating surface snail (like Janthina) needs much more justification to fit all the sources.

Track B — Historical evidence: the ancient dye industry was built on these snails

In the classical Mediterranean world, the famous purple/blue royal dyes (“porpora,” “purpura,” “porphyra”) are consistently connected to specific sea snails.

The same industry is described around Tyre and Sidon and other coastal areas, and it is known as an expensive and tightly controlled product.

This is important, because we find again and again that tekhelet (and also argaman) in Tanakh and in Chazal is not just a “nice blue” — it is a prestigious dye used in the Mishkan/Mikdash and also in high-status clothing.

We therefore have a strong historical context that the “tekhelet” of mitzvah belongs to that same family of Mediterranean dye-snail dyes.

Track C — Jewish sources connect tekhelet to “porpora” and to “hyakinthos”

Beyond the general historical context, there are specific Jewish sources that connect tekhelet directly to the porpora-dye world.

a) In some Midrashim, tekhelet is explicitly described with the term “porpora.”

For example, Pirkei deRabbi Eliezer (chapter 49) says:

“What does a king wear? Porporia…”

and it then connects that idea to Mordekhai’s “levush malkhut tekhelet” (Esther 8:15).

b) The Raavya (Berakhot siman 25) quotes in the name of a “Yerushalmi” (even though it is not in our Yerushalmi text) a contrast:

“between tekhelet and karti — between porpiri and prifinin…”

In any case, the point is that tekhelet is being spoken about in the language of porpora.

c) In the Jewish Greek sources of the period (the Septuagint translation, Aquila, Philo, Josephus), the word “tekhelet” in the Torah’s mitzvah contexts (tzitzit and the Mikdash) is translated with the Greek term “hyakinthos.”

That same word “hyakinthos” is also used in external Greek literature for a very expensive dyed fabric.

This shows clearly that the mitzvah-product was the same kind of high-value dyed material known in the broader world.

d) In some sources it appears explicitly that “hyakintha” is produced from the porpora/murex snails.

A striking example is in the Codex Justinianus (a Roman law code from the end of the Talmudic period), which speaks about the strict prohibition for private people to “undo” or dismantle the precious porpora dyes — whether in silk or wool — including “blatta,” “oxiblata,” and also “hyakintha.”

And it warns that if someone sells the wool dyed from the murex, he should know that his money and his head will be judged immediately.

In other words: from the porpora/murex (two names for the same dye-snail family), the authorities produced different shades/colors, and among them “hyakintha” — tekhelet.

Track D — Archaeological evidence

Archaeology strongly supports this identification:

Along the Mediterranean coast (including in Eretz Yisrael), archaeologists have found large mounds of broken murex shells near ancient settlements.

In several places, the remains of dye installations were also found.

This is exactly what we would expect if the chilazon was harvested and processed for dye on a large scale.

Track E — The comparison to “kala ilan” (fake tekhelet)

Chazal say in several places that “kala ilan” is a dye that looks exactly like tekhelet, and by eye you cannot distinguish between them.

The Geonim and the Arukh identify “kala ilan” as indigo (Arukh, entry “kala ilan”).

Indigo is a plant that produces a blue dye that is well known until today.

When you compare indigo-blue to the blue that can be produced from the Argamon Kehe Kotzim, they can indeed be extremely close — sometimes visually identical.

That lines up perfectly with the halakhic reality described by Chazal: real tekhelet is something valuable enough that people tried to counterfeit it with indigo.

Summary of the proofs

We have brought multiple independent tracks:

the meaning of “chilazon” in Chazal (a shelled snail),
the historical identity of the Mediterranean royal dyes with dye-snails,
direct Jewish sources linking tekhelet with porpora / hyakinthos and even murex,
archaeology of murex-shell mounds and dye sites,
and the comparison to kala ilan (indigo).

Some tracks are stronger than others, but the combination is, in my view, a very strong proof — close to certainty.

It is not reasonable that all these independent lines of evidence would “by accident” point to the Argamon Kehe Kotzim, while the real chilazon would be something else.

Why the other identifications were rejected — diyunon and Janthina

After seeing the above, we can also evaluate the other candidates that were suggested.

a) The diyunon (cuttlefish) does not fit any of the tracks:

It is not a “chilazon” (it has no shell, and it is not in the snail category that Chazal use).
There is no historical testimony that it was used as the famous ancient dye.
There is no archaeological evidence of a cuttlefish-dye industry.
The color produced in practice does not match the indigo-like “kala ilan” comparison, and can be distinguished.

It is worth noting that the Radzyn Rebbe himself assumed that the tekhelet of mitzvah is the same as the expensive Tyrian dyed fabrics described in Greek and Roman sources — but he did not bring the sources that describe which “chilazon” those fabrics came from.

It is very plausible that had he known those sources, he would have adopted the dye-snail identification.

b) Janthina:

Janthina is indeed a “chilazon” in the broad sense, and it exists in the Mediterranean, so it has some fit to the first track.

However, a very basic point is uncertain and disputed among experts: whether its secretion can dye wool in a stable way at all.

Some scientists argue that chemically it cannot produce a stable wool dye, and therefore it cannot produce usable tekhelet strings.

Others claimed success, but without a clear, reproducible description of the dyeing method.

As long as this basic question is unresolved, it is hard to build a practical halakhic identification on it.

This brings us to the next section: the main objections and doubts that are raised, and how to evaluate them.

Section 4 (ד): Main objections, questions, and “safek” claims about the Argamon identification

In the previous section we brought several strong tracks of evidence that the chilazon is the Argamon Kehe Kotzim.

Here we will deal with the main objections that are commonly raised.

Questions from Chazal’s descriptions of the chilazon

The Gemara (Menachot 44a) brings a beraita that gives several סימנים for the chilazon:

“Its body resembles the sea,”
“Its creation resembles a fish,”
“It comes up once in seventy years,”
“And with its blood they dye tekhelet; therefore it is expensive.”

At first glance, people try to read each line in the most literal way, and then they claim: “This doesn’t fit a murex snail.”

But when you learn the sugya carefully, it becomes clear that these lines are not a scientific field-guide.

They are short, “Gemara-style” descriptions, and each phrase has a natural way to understand it that fits well.

a) “Its body resembles the sea”

This is commonly understood as describing the camouflage of the snail in the water and on the rocks.

The Argamon Kehe Kotzim is a coastal snail whose outer appearance blends with the sea environment.

b) “Its creation resembles a fish”

The word “dag” in Lashon Chazal is not always the narrow zoological category we mean today.

Very often it simply means “a sea creature.”

We find this even in the Rambam, who sometimes uses “dag” broadly.

So this phrase can simply mean: it is a sea animal, not a land animal.

c) “It comes up once in seventy years”

Many Rishonim explain that this does not mean that the creature literally appears only once every seventy years.

Rather, it is a way of saying: it is difficult to find, it is not constantly available in large supply, and occasionally there is a “good year” of harvesting.

We also know historically that the industry had seasons and cycles, and even a relatively common snail can be “rare” in the sense that the usable harvesting opportunities are limited.

In addition, we need to remember a basic methodological point:

When later Rishonim “combine” separate lines from different sugyot into one literal picture, you can end up with a description that sounds like a legend.

The most reliable evidence is what Chazal themselves knew from direct reality, not later reconstructions.

d) “With its blood they dye”

Tosafot already note that the “blood” that is used for dye is not necessarily literal blood from a circulatory system.

It can refer to a dye-fluid that the animal secretes (Tosafot, Shabbat 75a ד”ה כי היכי).

The murex snail has exactly such a dye gland.

A Midrash that sounds “anti-renewal,” and Dr. Kaplan’s explanation

Some people bring a Midrash that says that tekhelet will be “hidden” until the future, and they argue from this that any modern renewal must be wrong.

(There are several versions and parallels of such Midrashim.)

Beyond the broader question of how to read Aggadah in halakhic practice, there is a basic point:

These Midrashim were said in periods when tekhelet was still practiced in reality, and the people speaking about it knew how it was produced.

So it is very hard to read them as a literal halakhic statement that “it is impossible to have tekhelet now.”

Dr. Shaul Kaplan suggested a specific “natural” reading: he claimed that lizards eat the chilazon on the shore, and therefore the chilazon is “hidden.”

But this reading does not fit the language well, and it rests on several shaky assumptions.

For example:

“Tzav” in the Midrash is a crocodile or sea creature, not necessarily a land-lizard.
“Semamiyot” in Chazal and Rishonim are spiders, not lizards (see, for example, Rashi / Ralbag / Metzudat Tziyon to Mishlei 30:28).
The Midrash describes something in the sea, not a shore-scene.

So even if we take the Midrash very seriously, it clearly requires careful explanation, and it does not produce a straightforward argument against renewal.

Objections from the Rishonim’s descriptions (Rambam, Rashi, etc.)

Another common move is to quote a Rishon and say: “He describes the chilazon in a way that doesn’t fit the Argamon.”

The most famous is the Rambam (Hil. Tzitzit 2:2):

“…and afterwards they bring the blood of the chilazon, and it is a dag whose eye resembles the eye of the sea, and its blood is black like ink, and in the Yam HaMelach it is found…”

Three questions are raised:

1) The Argamon is not a fish.

2) Its dye fluid is not black like ink; at first it is clear, and later it turns purple/blue.

3) The Argamon is not in the Dead Sea.

But once we compare the Rambam to his own words elsewhere, the difficulties largely fall away.

a) “It is a dag”

In his פירוש המשנה (Kelim 12:1), the Rambam explains the Mishna’s term “chilazon” (a part of a lock) and writes that it is shaped like a “tzadaf,” a shell, and it is named after “the shell of a sea creature called chilazon.”

So the Rambam certainly understood “chilazon” in the normal sense: a shelled sea creature — a snail.

When he writes “dag” in Hil. Tzitzit, he must mean it in the broad sense of “sea creature.”

b) “Yam HaMelach”

Rav Herzog and Rav Kapach explain that in Arabic usage, “the salty seas” (including the Mediterranean) can be called “Yam HaMelach,” whereas the Dead Sea is called “Yam HaMavet” (“Sea of Death”).

We find similar language in other halakhot in the Rambam, where it is clear that he means the Mediterranean coastal region, not the Dead Sea.

c) “Black like ink”

Rav Herzog raised an interesting possibility: the Rambam may be drawing on Aristotle (or another classical source) who describes the porpora snails as having a dark fluid.

Another simple point is that the fluid, when dried, can indeed look blackish before it is rehydrated and processed.

And in any case, the very fact that we find different descriptions among Rishonim (for example, Rashi says “its blood resembles the sea,” i.e., bluish) shows that their descriptions were not always based on direct observation.

A second example:

Rashi in a few places writes that the chilazon “comes up from the sea to the mountains once in seventy years.”

This is clearly a reconstruction from combining separate Gemara passages, and not a direct field-report.

The methodological conclusion is important:

Where Chazal’s sources can be read in more than one plausible way, we should not reject a strong identification just because one Rishon adopted a different reconstruction.

We cannot treat later descriptions as absolute “scientific data” when they were often derived from text-analysis and not from seeing the chilazon.

Claims of doubt: “maybe” arguments

Most objections raised today are not hard contradictions.

They are “maybe” claims — “perhaps the porpora of the ancient books is a different snail,” “perhaps the shell-mounds were for food,” “perhaps the archaeology means something else,” and so on.

Individually, many of these “perhaps” claims are simply not very plausible.

And even if you could raise a small doubt on each separate proof, the point is that we have a large collection of independent proofs.

When you combine them, the overall probability becomes very high, and the remaining doubts are no longer reasonable.

More broadly, halakhic decision-making does not require mathematical certainty.

The Ramban writes in a famous passage (Milḥamot Hashem, Sanhedrin 4a in the Rif pagination) that in the world of Torah, we often decide based on the most reasonable side, even without absolute proof like in geometry or astronomy.

So here as well:

Since the identification of the Argamon has strong, reasonable proofs, that level is sufficient for a halakhic conclusion — even if you can still imagine hypothetical alternatives.

A general “future doubt” claim

Some claimed: since several identifications were suggested in modern times (Radzyn, Janthina, Argamon), and each one rejected the previous, maybe a future discovery will reject the Argamon as well — and therefore we should not act now.

But this claim is not convincing:

a) In the scientific world, the Argamon identification has been the central identification for roughly 150 years, while the other proposals are late and marginal.
b) In every area of halakhah you could say: “maybe in the future a new opinion will appear.”

That is not how we decide halakhah.

c) If this were a “new leniency,” you might understand a fear that later it will collapse.

But here the renewal is a chumrah in a דאורייתא mitzvah (fulfilling tekhelet if this is the correct chilazon), and it is hard to justify refusing a strong mitzvah opportunity because of a speculative future scenario.

With this, we can move on to the broader halakhic question:

Even if the identification is strong, what level of obligation does it create, and how should a person weigh the practical considerations?

Section 5 (ה): Broader objections to renewing tekhelet — and how to evaluate them

In addition to the “technical” questions about the identification itself, there are broader arguments people raise against renewing tekhelet.

This section deals with the main ones.

“Without a mesorah you can’t identify it”

This argument is often associated with a position attributed to R’ Yosef Dov Soloveitchik zt”l: that without an unbroken mesorah, we have no way to decide what the chilazon is.

This sounds persuasive at first, but it is hard to accept as an absolute rule.

First, in many areas of Torah we rely on סימנים, logic, and factual evidence, even when we do not have an “eyewitness chain.”

Chazal themselves identify many דברים based on סימנים and reality.

Second, we sometimes rebuild lost ידע through physical evidence.

A classic example is the מקום המזבח on Har HaBayit:

When we returned in the days of Ezra, the Gemara says they found the foundations and based on that they knew the exact location (Zevachim 62a).

There were also nevi’im (Ḥaggai, Zekharyah, and Malakhi) who assisted, but the Gemara emphasizes the physical סימנים.

In other words: there is a concept that physical evidence can restore a lost detail.

Similarly, if we have strong textual, historical, and archaeological evidence about tekhelet, it is not reasonable to say that the תורה itself “blocks” us from using it.

What is true is something more modest:

Where the evidence is weak and speculative, mesorah has special weight.

But when the evidence is strong and convergent, it can function as a סוג of reconstructed knowledge.

“The identification is not 100% certain”

Some say: even if the Argamon is likely, it is not an absolute proof; therefore it is better not to do it.

But this is not how halakhah usually works.

In halakhic life we often act on strong likelihood, especially when the alternative is losing a דאורייתא mitzvah.

Here the question is not: “Can you prove it like a theorem?”

The question is: “Is this the most reasonable identification, supported by strong evidence, to the point that it is not reasonable to reject it?”

If the answer is yes, then in halakhah we treat that as sufficient.

(And as mentioned in the previous section, the Ramban already notes that Torah decision-making is not mathematical proof.)

“If it is ספק, you shouldn’t put it on, because you might be adding something wrong”

Sometimes people frame it as a “safek” in the opposite direction: if the Argamon is not the true chilazon, then the blue strings are not tekhelet, and maybe that is a problem.

But practically, blue strings are not forbidden.

If they are not tekhelet, they are simply colored strings.

There is no איסור in wearing colored strings (the Torah never said that only white is permitted; it said that tekhelet has a mitzvah-status).

At worst, a person did not fulfill tekhelet.

So the fear of “adding something אסור” is not really grounded.

The only real halakhic concerns would be secondary issues (for example, if someone would mistakenly make a berakhah on the dye itself, or if a person would treat it as “definitely tekhelet” in places where ספק should matter).

But on the basic level: wearing the strings is not an איסור.

“Yohara” (showing off) and “casting aspersions on the previous generations”

A social-psychological objection is sometimes raised:

Maybe wearing tekhelet today is yohara — acting “more frum than everyone,”
or maybe it looks like you are judging those who do not wear it.

But this is not a convincing halakhic argument.

If tekhelet is a mitzvah, fulfilling it is not “showing off.”

People keep many mitzvot that others don’t keep (different minhagim, different chumrot, different understandings), and we do not call that yohara automatically.

Also, we do not “blame” earlier generations for not wearing tekhelet.

They did not have access to it.

If today we can reasonably restore it, that is not an accusation; it is פשוט a שינוי in reality.

If someone personally feels that in his environment it will create conflict or arrogance, he should be honest about that and consult his Rav.

But as a כלל argument, it is weak.

“Most Gedolim do not wear it, so it must be wrong”

This is probably the most common practical objection:

If it is so ברור, why don’t the Gedolei haDor all wear it?

There are several answers.

a) On a purely halakhic level, we do not have a functioning Sanhedrin and a binding כלל ruling process today.

We follow poskim and מסורת psak, but there is no single institution that can “close” every open question.

So the fact that there is not universal adoption does not automatically mean the evidence is wrong.

b) More importantly, the reality is that many talmidei ḥakhamim did not learn the full sugyot together with the scientific and archaeological material.

It is a complex field, and most people simply do not have time to research it in depth.

So the “majority” here is not necessarily a majority of people who have examined the full evidence.

c) And even among those who examined it, this is still a developing conversation.

In the last decade-plus, more and more serious talmidei ḥakhamim have engaged it, and some have changed their minds.

It is therefore not reasonable to say, at this stage, “the halakhah has already been decided.”

A complex sugya needs time to clarify, and it is not plausible that it becomes “sealed” based only on the earliest reactions, within a short period.

With these broader objections addressed, we can now ask the practical halakhic question:

Assuming the identification is strong, what level of obligation does it create, and how should one relate to it in practice?

Section 6 (ו): The level of obligation of tekhelet

Given the situation described above, there are a few puzzling points that are hard to understand:

Why do most poskim not address this sugya at all?
Many of those who reject tekhelet relate to it very briefly—one sentence or two—while on other details in halakha they write long and detailed teshuvot.
Almost all the rejecters reject because of safek—why are they not worried to be machmir because of safek?
We saw a few treatments of this matter that are complex, leaning this way and that, and the matter needs explanation.

In my view, there are a number of factors that bring about this unique approach: for example, that the sugya is new, and as long as it has not been clarified people continue to hold by the accepted minhag until now; and also that this sugya requires using non‑Torah tools such as history and archaeology. But it seems clear that one of the factors is the perception that tekhelet is not a “burning issue”, since in any case we have tzitzit even without tekhelet. Here we need to enter the question: what is the level of obligation of tekhelet?

The opinions on this matter

On this subject there are different opinions among the Acharonim. There is an approach that holds that tekhelet is not an obligation, but an addition to the mitzvah of tzitzit.

So writes the Penei Yehoshua (Bava Metzia 61b, s.v. “Mihu”):

“…for we hold that tekhelet does not prevent the white… and the tekhelet written in the Torah is only for the mitzvah min hamuvchar…”

And so it appears from the words of the Arukh HaShulchan (siman 9, se’if 12):

“…And because of our sins, since we were scattered we do not have tekhelet, and we do not know anything of it at all, and all our tzitzit are white. Nevertheless, we fulfill the mitzvah properly, since it was already explained that tekhelet does not prevent the white.”

In contrast, there is an approach that holds that tekhelet is a full obligation. When a person has the ability to put tekhelet, and he wears tzitzit without tekhelet, he is nullifying a positive mitzvah (more precisely—half of a positive mitzvah, since tekhelet and the white are counted as one positive mitzvah; but this makes no practical difference for halakha, since in the end he is nullifying a Torah command). Only when there is no possibility to put tekhelet is it permitted to wear tzitzit of white.

So asks the Sha’agat Aryeh (siman 32): how is it permitted to wear white tzitzit, in his time when there was no tekhelet:

“…How can he put white and wear this tallit—behold he is doing an aveirah in wearing it, and he transgresses the positive mitzvah of tekhelet?”

And his answer is that in a time when tekhelet is not available, we are in the category of ones (coerced), and therefore it is permitted for us to go with white tzitzit; but in a time when there is tekhelet, and we are not ones, indeed it is forbidden to wear white tzitzit.

[These words are puzzling—seemingly, even when it is impossible to obtain tekhelet, we are not ones, since one could avoid wearing a four‑cornered garment at all?! The Sha’agat Aryeh answers that this is understood based on the foundation brought in the words of the poskim: the mitzvah of tzitzit is not a lo ta’aseh but a positive obligation. The Torah did not say “Do not wear a garment without tzitzit”, but in a positive formulation: “They shall make for themselves tzitzit”. Therefore, a person who does not wear a four‑cornered garment is not transgressing. But he also is not fulfilling the mitzvah of tzitzit. The Torah therefore framed the mitzvah so that one who wears a four‑cornered garment is obligated to place tzitzit in it. Accordingly, one who places white without tekhelet when he is ones to obtain tekhelet is still fulfilling the mitzvah of tzitzit, because the Torah’s way of obligating the mitzvah is via wearing such a garment. In contrast, one who completely avoids wearing a four‑cornered garment is not a “sinner”, but he is refraining from fulfilling the mitzvah; and on this the Sha’agat Aryeh writes that he is considered as one who disqualified himself from fulfilling the mitzvah—an aveirah.]

And so writes Rav Yosef Perla (Commentary on Sefer HaMitzvot of Rav Saadia Gaon, p. 171, s.v. “Ve‑omnam”):

“…white without tekhelet was permitted only when he has no tekhelet; but when he has… it is forbidden to wear the garment, for it is as one who actively nullifies the aseh of tekhelet.”

“…but certainly, when he has tekhelet and white and he places in his garment only one of them… he is doing an aveirah when he wears it, as one who transgresses an aseh with his hands.”

Proofs that tekhelet is a full obligation

In my view, looking at the sources shows clearly like the Sha’agat Aryeh and Rav Yosef Perla: tekhelet is a full obligation and not only a mitzvah min hamuvchar. We will bring here the main points; one who wants to expand should see the article below, “Tekhelet in tzitzit—mitzvah min hamuvchar, or a full obligation”.

As we saw in the citations from the Penei Yehoshua and Arukh HaShulchan, the main proof they bring that tekhelet is not an obligation is from the Mishnah in Menachot (perek 4, mishnah 1), which says that tekhelet does not prevent the white. Seemingly, indeed, the simple meaning of the Mishnah is like them—that one can suffice with white without tekhelet, and tekhelet is only an addition to the mitzvah. However, when you look closely, it seems the meaning of the Mishnah is different.

The mishnayot there in Menachot (perek 3 mishnah 5 – perek 4 mishnah 4) list mitzvot whose parts prevent one another, as opposed to mitzvot whose parts do not prevent one another. “Prevent” means that the parts of the mitzvah depend on one another, and without one part there is no mitzvah at all. So, for example, with the four parashiyot of tefillin (there, perek 3 mishnah 7), the mitzvah is not fulfilled at all without all four—if someone is on a deserted island and he has only three parashiyot, there is no point in putting on tefillin in that form, and he must refrain. Therefore, in that Mishnah the four parashiyot “prevent one another”.

In contrast, the Mishnah continues and says: four tzitziyot prevent one another. Meaning: all four tzitziyot together are one body of mitzvah; if one is missing, the mitzvah is not fulfilled at all. But if a garment’s tzitzit had tekhelet and was missing white (or the opposite), he has still fulfilled part of the mitzvah; therefore tekhelet does not “prevent” the white, and the white does not “prevent” tekhelet.

And so the Rambam copies the rule of “does not prevent” (Hilchot Tzitzit, perek 1, halakha 4):

“Tekhelet does not prevent the white… How? If he has no tekhelet, he makes white alone…”

Meaning: the whole meaning of “does not prevent” is only for a case of ones, when a person has no way to obtain tekhelet; then he makes white alone. But if he does have the ability to obtain it, he is obligated to put tekhelet, and it is forbidden to suffice with white alone.

And so writes Sefer HaChinukh (mitzvah 386):

“…And what they said, that tekhelet does not prevent the white and the white does not prevent the tekhelet… for example us today, when we do not find tekhelet, that we should not refrain because of this from putting white strings without tekhelet in the tallit, and we make a berakha on them, as if it were complete with the tekhelet.”

The nafka minah of “does not prevent” is specifically in a situation of ones, such as a time when there is no tekhelet. We might have thought that in such a situation there is no point in putting tzitzit at all, and it would be forbidden to make a berakha on such incomplete tzitzit; and the rule of “does not prevent” teaches that there is still a mitzvah with white alone, and we bless on white tzitzit just as we bless on complete tzitzit of white and tekhelet. But this does not speak at all about a situation where tekhelet is available and one chooses not to put it.

And so says Rashi (in a responsum brought by the Ramban in Milchamot Hashem, Shabbat 12a of the Rif’s pages):

“For the main mitzvah is with tekhelet, and one who fulfills white without tekhelet does not have a complete mitzvah, but one of the two…”

Meaning: the white is only half a mitzvah, “one of the two”, and therefore, if we have the possibility, we are obligated to complete the second half—the tekhelet.

And we will finish the proofs with one more citation: the Gemara in Menachot 43b says:

It was taught: Rabbi Meir would say: the punishment for white is greater than the punishment for tekhelet. To what is the matter comparable? To a flesh‑and‑blood king who said to two of his servants: to one he said, “Bring me a seal of clay”, and to one he said, “Bring me a seal of gold”. They both were negligent and did not bring it—whose punishment is greater? You must say: the one to whom he said, “Bring me a seal of clay”, and he did not bring it.

Meaning: lacking tekhelet is an aveirah and there is punishment for it, only that the punishment is less severe than the punishment for lacking white. The reason for the difference is not a halakhic difference between them, but only a practical difference—tekhelet is expensive, “a seal of gold”, and therefore one who refrains from putting tekhelet has mitigating circumstances that reduce his punishment. This also comes out from the Rambam (Hilchot Tzitzit, perek 2, halakha 9), who brings this statement.

The practical ramifications of this matter

From this understanding, that tekhelet is a full obligation, it follows first of all that one cannot belittle this sugya and dismiss it with weak claims. If it is indeed tekhelet, then we are obligated to put it, and when we do not do so we are nullifying a Torah positive mitzvah. It is possible that after investigation a person will conclude that it is not tekhelet; but the investigation has to be done with full responsibility and thoroughness, like any other positive mitzvah.

Since in my view it is indeed proven that this is tekhelet, as we expanded above, it follows that today, when tekhelet can be obtained, one is obligated to put it in the garment, and this is not merely a pious practice (see the haskamah of Rav Dov Lior shlita to the sefer “Chevel Nachalato” (p. 10), who agreed with these words).

And more than that—in my view it follows that today one should not wear white tzitzit. As Rav Yosef Perla wrote, which we brought above:

“…but certainly, when he has tekhelet and white and he places in his garment only one of them… he is doing an aveirah when he wears it, as one who transgresses an aseh with his hands.”

And if for some reason that is not in the category of ones, the person is not putting tekhelet now in his garment, it is better in my view that he should not wear a tzitzit garment at all, rather than wear white tzitzit. Because by the basic halakha a person is obligated in tzitzit only if he wears a four‑cornered garment, and he is not obligated to wear a four‑cornered garment and obligate himself in tzitzit—this is only a midat chasidut (Shulchan Arukh Orach Chayim 24:1).

These words certainly sound strange to many readers, because we got used to wearing white tzitzit for many years. Indeed, as the Sha’agat Aryeh explains, this din was correct in his time when there was no tekhelet, and then we were ones regarding this mitzvah; but from the time tekhelet was renewed and can be obtained, there is no longer ones, and the din returns to its original basis, that one should not wear only white tzitzit.

I will add one more clarification, because I have seen more than once that people misunderstand, as if the intent is that someone who started to wear tekhelet tzitzit is now obligated to go only with tekhelet and forbidden to wear white tzitzit. Of course, that is not the intent—this does not depend at all on whether the person once wore tekhelet; rather it comes from the mitzvah itself, and everyone is obligated in tekhelet equally.

Even though this is how it appears to me for halakha le‑ma’aseh, I will not refrain from bringing another opinion as well—the opinion of the Rosh Yeshivah Rav Ra’am HaKohen is that indeed there is a full obligation to put tekhelet, but one who wears white tzitzit is not considered a transgressor, and when for some reason tekhelet is not being put, in the meantime one may wear white tzitzit.

I will add a few common practical points on this matter, as it appears to me:

A person who does not have enough money to buy tekhelet—the accepted rule is (Rema’s gloss, Orach Chayim siman 656 se’if 1; and Mishnah Berurah there, se’if katan 8) that a person is not obligated to spend more than a fifth of his money to fulfill a positive mitzvah. Therefore, a person who does not have money equal to five times the price of tekhelet is considered ones, and according to all opinions may wear white tzitzit.

A person who is afraid to wear tekhelet tzitzit all day, out of concern that the tzitzit will tear—such as soldiers, laborers, and children—can wear tekhelet tzitzit only during tefillah, and the rest of the day go without tzitzit. This option appears in the Shulchan Arukh (Orach Chayim 24:1): “At least he should be careful to be wearing tzitzit at the time of tefillah”. And it is better to act this way than to wear white tzitzit the rest of the day, since in that case he is nullifying a positive mitzvah.

A person who wears one garment with tekhelet and the other with only white tzitzit (for example, tallit gadol and tallit katan)—this does not exempt him, since each garment has its own obligation. The fact that he has tekhelet on one garment does not permit him to nullify the mitzvah on the second garment, just as a person may not wear one garment with tzitzit and the other without tzitzit. Therefore, if he currently has only one set of tekhelet tzitzit, he should wear only one tzitzit garment.

Regarding someone who borrows from his friend white tzitzit—the halakha is that a borrowed tallit is exempt from tzitzit. And the poskim (Shevut Yaakov chelek 2 siman 23; Sha’arei Teshuvah Orach Chayim siman 8 se’if katan 18; Mishnah Berurah siman 14 se’if katan 11; and more) distinguish between two situations:
If he borrowed a tallit only to wrap in it for honor, for example to get an aliyah or to go before the amud—then it is a borrowed tallit, it is exempt from tzitzit, and he should not make a berakha on it.
If he borrowed a tallit in order to fulfill the mitzvah—then we assume this is not a standard loan, since his intention is to fulfill the mitzvah and it cannot be fulfilled with a borrowed tallit. Rather, they define it as a gift on condition to return; therefore in such a case he makes a berakha on it.

It follows for our matter: a person should not borrow from his friend white tzitzit in order to fulfill the mitzvah and make a berakha, because then he would also be obligated in tekhelet. But he may borrow white tzitzit in order to get an aliyah and the like, and he should intend that he is not acquiring it, but taking it only as a loan; then he is not obligated in tzitzit and he does not make a berakha on it.

Regarding a public tallit, such as a synagogue tallit—the poskim (Bi’ur Halakha to siman 14 se’if 3, s.v. “She’elah”, and more) define a public tallit as a tallit of partners, because the whole public are partners in it. According to this, the tallit is not like a borrowed tallit that is exempt from tzitzit; rather each partner is obligated in tzitzit when he wears it. If so, seemingly one should not wear a synagogue tallit when it does not have tekhelet. But in practice, today most synagogues are defined as an amutah (association), and then the property is not considered joint property of the entire public. Therefore, one who is in the synagogue does not necessarily acquire the tallit as a partner, and the practical halakhic ramifications are different.

Section 7 (ז): Practical placing of tekhelet tzitzit

Points of discussion in this matter

When we renew the mitzvah of tekhelet in tzitzit, we need to clarify again the way it is done—meaning, how tekhelet fits into the tying of the white tzitzit that are familiar to us. This is not simple, because there are many details and many opinions.

In this respect, the sugya of tekhelet is unique. In many areas there are disputes, but usually there is psak from earlier generations—Shulchan Arukh and its major commentators—who decide between the Rishonim. Here there is no psak of Shulchan Arukh, because tekhelet was not practical in that period; and as is known, Shulchan Arukh deals only with halakhot that applied in his time. Therefore, when tekhelet returns, the practical decisions must be clarified anew from the sugyot.

It should also be noted that the different minhagim among the communities of Israel regarding tying tzitzit do not fully help us when we come to put tekhelet. This is because the poskim state explicitly (Tur, siman 11, and more) that the accepted minhag in tying tzitzit is not like the din of the Gemara, because the din of the Gemara was said for tekhelet tzitzit, and with white tzitzit other minhagim developed. It turns out that we cannot rely on minhag, and we have to return to the sugyot of the Gemara and clarify them, to know the din for putting tekhelet.

However, in certain points there is no difference between tekhelet and white, and in those points we can learn from the words of the poskim and from minhag Yisrael with white what the din will be also with tekhelet.

We can list here five different discussions:

What is the number of tekhelet strings, out of the eight strings of the tzitzit?
Are the wrappings done mainly with tekhelet, or with a combination of tekhelet and white?
What is the number of chulyot that are wrapped in the tzitzit, and what is the number of wrappings in each chulyah?
What is the form of the chulyot?
How the knots are combined with the chulyot.

Between these discussions there is a difference in their level of severity. The first discussion, about the number of strings, is the most fundamental; if one put fewer tekhelet strings according to one view, he will not fulfill his obligation according to the views that require more tekhelet strings. The other matters, however, are not me’akev, and almost however one did it, he will fulfill his obligation according to all views, even if it is not lechatchilah.

Since there are five separate discussions here, the number of possible methods is very large, because every tying method needs to combine a decision in discussion A with a decision in discussion B, and so on. In practice we indeed find among the poskim seven different methods and even more. A summary appears in articles (for example, Rav Yehudah Rak, Techumin 16, pp. 412–432; an expanded version appears on the Petil Tekhelet site). Here we will not lay out all the combinations, but will present each discussion on its own, and the combination that seems to me for halakha le‑ma’aseh.

Discussion A — Number of tekhelet strings

Regarding the number of tekhelet strings, there are three opinions among the Rishonim:

Rashi (Menachot 38a, s.v. “Ha‑tekhelet”), Tosafot (ibid.), and additional poskim: two strings out of the four (meaning: after folding, there are four tekhelet strings out of the eight).
The Ra’avad (hasagot on Rambam, Hilchot Tzitzit 1:6) and the Arukh (entry “Tekhelet”): one string out of four (two out of eight).
The Rambam (Hilchot Tzitzit 1:6): only half a string is tekhelet (one out of eight).

Let us look at Chazal’s sources. In Midrash Bamidbar Rabbah, parashah 18, paragraph 3, it says:

“…Korach said to him: a tallit that is entirely tekhelet does not exempt itself, and four strings exempt it?!”

Meaning: in an all‑tekhelet tallit there are four tekhelet strings. This fits the Ra’avad (four full strings before folding) or the Rambam (four strings after folding), but not Tosafot.

And in the Sifrei on parashat Shelach, piska 115, it says:

“With how many gedilim do you make it? Not less than three—these are the words of Beit Hillel; and Beit Shammai say: three of wool and a fourth of tekhelet; and the halakha is like Beit Shammai.”

This is explicit like the Ra’avad: in each tzitzit there are three white strings and one full tekhelet string.

However, in the Sifrei on parashat Ki Tetze, piska 234, it seems like Tosafot:

“How many gedilim are made? Not less than three strings, like the words of Beit Hillel; Beit Shammai say: from four strings of tekhelet and four strings of white.”

Meaning: after folding there are four tekhelet and four white.

But this girsa is not clear. There are manuscripts with a different girsa (see the Finkelstein edition), and difficulties were already noted in the printed wording itself (in that version, Beit Hillel and Beit Shammai use “strings” differently). In addition, there is a contradiction between the midrashim and even within the Sifrei’s piskot. This supports rejecting that unclear girsa and aligning it with the other sources that are not in doubt. Indeed, the Gra in his notes emends this version and matches it to the nusach in parashat Shelach.

Accordingly, the clear sources are like the Ra’avad (and some can also be read like the Rambam), whereas for Rashi and Tosafot there is essentially only one source whose girsa is doubtful. Therefore, it seems one should rule like the Ra’avad—to put one full tekhelet string.

And so the Gra decides: in his commentary to Ra’aya Mehemna (Pinchas 228) he brings the opinions and writes on the Ra’avad: “for that is the main [view]” (see also Rav Tavger’s article on the Gra’s shita on the Petil Tekhelet site).

Discussion B — Are the wrappings mainly tekhelet, or a combination of tekhelet and white?

The Rambam (Hilchot Tzitzit 1:7) holds that only the first and last wrapping are wrapped in white, and all the other wrappings are in tekhelet.

In contrast, the Ra’avad (there, in his hasagot) holds that one wraps tekhelet and white alternately.

And the shita of Rav Amram Gaon (“Ga’onika”, vol. 2, pp. 330–331) and Tosafot (Menachot 39a, s.v. “Lo”): chulyot of tekhelet and white alternately.

This dispute comes from a fundamental difference in how they understand the relationship between tekhelet and white in tzitzit.

The Rambam (Hilchot Tzitzit 1:3) holds that there is a difference in role: tekhelet’s role is to wrap around the white, as it says, “They shall place on the corner tzitzit a thread of tekhelet”—the tekhelet must be “on” the white, wrapping and twisting around it.

Rav Amram Gaon and the Ra’avad, however, hold that tekhelet and white do not have different roles; rather, tzitzit contains two types that are equal in their role—like the four species, which come together without one “serving” the other. Therefore they wrap with both equally. (This is explicit in the Ra’avad’s wording: “And why more in tekhelet than in white?”)

The Rambam’s reading seems to me the plain meaning of the pasuk. And even if we define this as an even safek, it seems better to act like the Rambam: according to him, wrapping in tekhelet is the core Torah din, while according to the Ra’avad, the alternation is not an essential definition but a hidur. It is better to give up a hidur according to the Ra’avad than to give up the core Torah din according to the Rambam.

At first glance, one might think these decisions contradict: the Rambam’s “tekhelet wraps” approach fits best with his view that only half a string is tekhelet; while the Ra’avad’s “equal types” approach fits best with having one full tekhelet string. Yet in truth there is no contradiction: even if tekhelet’s role is to wrap, one can still take one full tekhelet string and use it as the wrapper. There is no necessity to minimize to half a string. Moreover, it seems that one who put a full tekhelet string like the Ra’avad would not invalidate according to the Rambam, because adding does not detract—“it is no worse than white”.

According to Tosafot, who have two tekhelet strings, tekhelet cannot be only “the wrapper”, because then why have an additional tekhelet string that plays no role in wrapping. But according to the view that there is one tekhelet string, it can still be understood as the wrapper—even if theoretically one could have dyed only half.

Indeed we find a shita that says: “…that it has six white wool strings and two wool strings dyed tekhelet, and one of those two is the one that wraps on the seven…”

It should be added that even according to the shita that the wrappings are mainly tekhelet, the first and last wrapping need to be in white, as in the Gemara (Menachot 39a):

It was taught: when he starts, he starts with white—“the corner” means the same type as the corner; and when he finishes, he finishes with white, “we go up in holiness and we do not go down”.

And so the Rambam rules (Hilchot Tzitzit 1:7) that all wrappings are in tekhelet except the first and the last.

Discussion C — Number of chulyot, and the number of wrappings

In the Gemara (Menachot 39a) it says:

“And what is the measure of a chulyah? It was taught: Rabbi says: enough that he wraps, and repeats, and triples.”

“It was taught: one who reduces should not reduce below seven, and one who adds should not add above thirteen…”

The Rambam (Hilchot Tzitzit 1:7–8) and many Rishonim explain that in each chulyah one wraps three wraps, and the number of chulyot is from seven to thirteen.

The Ra’avad (comment on Hilchot Tzitzit 1:7) explains that the number of wraps in a chulyah is between seven and thirteen (and “wraps, repeats, triples” refers to the tekhelet wraps; according to his earlier view that wrapping alternates, a chulyah of seven wraps includes four white and three tekhelet).

At first glance it may seem Ashkenazim ruled like the Ra’avad, since the accepted Ashkenazi minhag is to wrap in each section a number of wraps from seven up to thirteen (7, 8, 11, 13). But in truth, one should know the basic ruling is like the Rambam. The Shulchan Arukh (siman 11 se’if 14) makes clear that the count of 7‑to‑13 wraps is minhag, not obligation. The Mishnah Berurah (ibid., se’if katan 70) mentions another minhag (10, 5, 6, 5—common among Sephardim) where most sections have fewer than seven wraps. And from the basic halakha the Mishnah Berurah (ibid., se’if katan 66) rules that one can even suffice with one chulyah of three wraps, and the tzitzit is kosher.

And so the Tur (siman 11) says:

“In the time there was tekhelet, one had to be careful in the wrapping to make seven chulyot as they are explained in the Gemara; and now that we do not have tekhelet… we do not need to be careful with the chulyot…”

From this it follows that when we returned to putting tekhelet, we should make seven chulyot, and in each at least three wraps.

Discussions D and E — The form of the chulyah, and how the knots are placed between the chulyot

The Gemara does not describe the physical “form” of a chulyah, and there are different minhagim in Israel regarding tying the chulyot of white tzitzit.

According to the minhag of Ashkenazim and Sephardim, a chulyah is made by tying a double knot, wrapping a number of wraps, and again tying a double knot.

According to the minhag of Yemenites (whose source is in the Rambam, as is proven in his responsa, siman 138), there is no knot between one chulyah and the next. Rather, the wraps themselves are made in a way that creates an internal knot that holds the chulyah, and between one chulyah and the next there is a gap without a knot.

Now we need to connect this to the matter of knots.

As we said, according to most Rishonim, from the din of the Gemara one needs at least seven chulyot. In contrast, in Midrash Tanchuma (Warsaw edition, parashat Korach, siman 12, s.v. “Mentzapach”) it appears that tzitzit has five knots. Seemingly this does not fit: if there are seven chulyot, there are eight knots (one at the beginning and one after each chulyah).

On this question there are four directions:

The Gemara meant chulyot like the Yemenite minhag, where there is no knot between chulyot. One can tie seven or thirteen chulyot without knots at all. The Midrash adds that in addition to the chulyot one also ties five double knots in certain places (Sefer HaChinukh, mitzvah 386).
Tosafot (Menachot 39a, s.v. “Lo”) explains that the knot is after every pair of chulyot (fitting their view that the chulyot alternate white and tekhelet), and this yields five knots for seven chulyot.
The Gemara speaks about tekhelet time, and then indeed there were eight (or fourteen) knots. The Midrash speaks about a time without tekhelet; elsewhere in Midrash Tanchuma it is mentioned that tekhelet had already been hidden away in its days. It describes the minhag of only four chulyot and five knots, as practiced today with white among Ashkenazim and Sephardim (Beit Yosef on siman 11 brings this in the name of the Ittur, and in his view the loss of tekhelet necessarily reduced the knots to five instead of eight).
The Rambam did not rule the Midrash’s five‑knot statement at all, and did not mention five knots for either tekhelet or white—meaning, he saw it as a local minhag, not a binding din for all Israel.

In our generation, many who put tekhelet adopted the Yemenite‑style chulyot. Some tie only one double knot at the beginning and one at the end, and between them seven or thirteen such chulyot (as in direction d). Others tie thirteen Yemenite chulyot and add five additional double knots between them (as in direction a).

But in my view, Ashkenazim and Sephardim have no reason to change from the accepted minhag regarding the form of the chulyah. The matter of chulyot is not something that belongs specifically to tekhelet; even with white there must be chulyot, at least one chulyah (Mishnah Berurah siman 11 se’if katan 66). Ashkenazim and Sephardim practiced to make chulyot in the form of: double knot, wraps (three or more), double knot. On this point we have accepted minhag and practical psak, and there is no reason to change, even if it is not me’akev.

Only the number of chulyot needs to change when there is tekhelet: instead of four chulyot, one should tie seven chulyot, as in the din of the Gemara. Consequently the number of knots will be eight, not five. In theory one can also do thirteen chulyot, but this is not practical, because a gidil with fourteen double knots will take up most of the tzitzit; and by basic halakha one should try that the gidil take up only a third of the tzitzit (Rema, Orach Chayim 11:14). This fits direction c: the Midrash speaks about no‑tekhelet time, while in tekhelet tzitzit there will be more than five knots.

And so rules Rav Tzvi Shechter (in “Tekhelet: The Renaissance of a Mitzvah”, Hebrew section, p. 40): do not change the form of the chulyah; rather make seven chulyot with double knots, and in each chulyah at least three wraps.

How many wraps should one wrap in each chulyah?

As we saw, the minimal number of wraps in a chulyah is three; but one can add, as Ashkenazim and Sephardim add in white tzitzit. Therefore, it seems to me: if the tekhelet string is short, one should do only three wraps in each chulyah—21 total. But if the string is long enough, it is preferable for Ashkenazim to wrap 39 wraps total, as they did with white: 39 wraps corresponding to “Hashem Echad”.

To accomplish this with seven chulyot in a way that is practical and balanced, one can distribute the wraps so the chulyot are nearly equal and also “we go up in holiness” (smaller number earlier, larger later). One practical distribution is the following (yielding 39 total): the first chulyah begins with one white wrap, then four tekhelet wraps; the next two chulyot are five tekhelet wraps each; the next three are six tekhelet wraps each; and the final chulyah is five tekhelet wraps and then one white wrap.

And by the same principle, one who had a minhag with white to wrap 26 wraps, corresponding to the Name Havayah, will wrap with tekhelet: 3, 3, 4, 4, 4, 4, 4.

Practical summary of placing tekhelet tzitzit, based on what was said above:

Take three white strings and one tekhelet string (Ra’avad strings).
Thread them through the hole of the garment, and tie a double knot.

Chulyah 1:

Wrap one wrap in white.

Bring the white string close to the other strings, and wrap on all of them four wraps in tekhelet.

Tie a double knot.

Chulyot 2–3:

Wrap five tekhelet wraps; tie a double knot.

Chulyot 4–6:

Wrap six tekhelet wraps; tie a double knot.

Chulyah 7:

Wrap five tekhelet wraps.

Bring the tekhelet string close to the other strings, and wrap on all of them one wrap in white.

Tie a double knot.

It was taught: Rabbi Meir would say: How is tekhelet different from all other colors?

Because tekhelet is similar to the sea, and the sea is similar to the sky, and the sky to the Kisei HaKavod,

as it says: “And under His feet was like a work of sapphire brick, and like the essence of the heavens, for purity”; and it says: “Like the appearance of a sapphire stone, the likeness of a throne.”

(Menachot 43b)

The Tekhelet and Its Renewal